Optimized RF safety monitoring for cerebellar magnetic resonance imaging at 7T

Abstract

The primary objective of this thesis is to develop optimized RF safety assessment techniques for cerebellar imaging using 7T MRI systems, with a specific focus on Spinocerebellar Ataxias (SCAs). Due to the unavailability of detailed electro- magnetic simulation data from the manufacturer, this study focused on predicting the electromagnetic behavior of the Nova 8Tx/32Rx coil’S 8 pTx channels to en- sure accurate and safe imaging. Accurate prediction of the coil’s electromagnetic performance is essential for both RF safety and imaging quality, particularly in managing RF exposure and minimizing tissue heating. The approach involved replicating the electromagnetic fields of the Nova coil through simulations, validating these predictions against experimental measure- ments, and implementing an algorithm for calculating the temperature-based Virtual Observation Points (tVOPs) in future works for rapid RF safety assess- ments. While the initial simulations captured key aspects of the coil’s B1+ field distribution, discrepancies between predicted and experimental results revealed challenges, especially in random-phase shimming configurations. The limitations of using ideal current sources and the reduced dataset for optimization highlighted the need for more comprehensive data and realistic models. The findings underscore the importance of integrating empirical measurements with refined simulations to bridge the gap between theoretical models and real- world performance. Future work should focus on enhancing current source mod- els, mitigating noise and experimental inaccuracies, and expanding the applica- tion of these techniques to broader clinical scenarios. By addressing these chal- lenges, this research can contribute to improving both the safety and quality of high-field MRI, ultimately advancing its reliability for both clinical and research applications.